Camera exposure control



May 13, 1952 D. B. DORSEY CAMERA EXPOSURE CONTROL 4 Sheets-Sheet 1 Filed Aug. 18, 1948 May 13, 1952 D. B. DORSEY CAMERA EXPOSURE CONTROL Filed Aug. 18, 1948 4 Sheets-Sheet 2 ga /Z2?? Jazz/24451350 7 L" v //4% Q42 May 13, 1952 D. B. DORSEY 2,596,328

CAMERA EXPOSURE CONTROL Filed Aug. 18, 1948 4 Sheets-Sheet 3 May 13, 1952 D. B. DORSEY CAMERA EXPOSURE CONTROL 4 Sheets-Sheet 4 Filed Aug. 18, 1948 "mum wwerzfi j/ZWZ Z0 Z00 %M:3%; x @212 Patented May 13, 1952 UNITED STATES ENT OFFICE This invention relates to a camera, and more particularly to improvements in photographic and motion picture cameras provided or used with a photo-electric or other light sensitive ex-- posure meter.

It is an object of this invention to provide in a camera control, means for so relating the various adjustable members of the camera, as for example the shutter speed adjustment means, or exposure interval setting means, and the diaphragm adjustment means, or exposure opening setter, that setting of the control relative to one of said adjustment means in accordance with scene brightness, as determined by the direct reading of the exposure meter, will automatically set the other adjustment means at the proper setting.

A more specific object of the invention is to provide in such a camera control as above stated, means whereby the camera having once been set according to the scene brightness, the exposure opening setting or diaphragm adjustment will be automatically varied or changed the proper amount by the adjustment of the shutter speed adjustment means.

Heretofore, in the use of an exposure meter to determine the proper setting of a camera it has been necessary first to take a reading of scene brightness in order to obtain a light rating and thereafter by utilizing that rating, determine by relative adjustment of the complicated series of dials an exposure opening or diaphragm setting and a shutter speed or exposure interval for a particular film with which the camera is loaded. It frequently happens that after this complicated series of adjustments or calculations have been made that the shutter speed or the exposure opening thereby determined is beyond the range of the particular camera or the scene brightness has changed so that the entire series of operations must be duplicated.

The present invention seeks therefore to simplify the adjustments and calculations necessary to set a camera by the use of an exposure meter in such manner that it is merely necessary at the time of taking a picture to first make a measurement of the scene brightness in order to obtain a light rating and thereafter make a single adjustment in the camera according to the exact reading of the meter without further calculations.

An ancillary object of the invention is to provide in a focal plane shutter, interchangeable lens and diaphragm type camera, control means which on adjustment in accordance with the measurement of the scene brightness automati- 1 Claim. (CI. 95-64) cally effects the proper setting of the exposure framing frequency.

Other and further objects and advantages of the invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

Fig. 1 is a front view of a focal plane shutter, interchangeable lens and diaphragm type camera embodying the present invention;

Fig. 2 is a front view similar to Fig. 1 with lens-diaphragm unit removed and additional internal parts shown in dotted lines;

Fig. 3 is a top plan view of the camera of Figs. 1 and 2 Fig. 4 is a fragmentary view in perspective of the camera of Figs. 1 and 2;

Fig. 5 is an enlarged, fragmentary view invertical section taken substantially along the line 55 of Fig. 1;

Fig. 6 is a fragmentary view in vertical section taken substantially along the line 6--6 of Fig. 1;

Fig. '7 is a fragmentary view in vertical section taken substantially along the line 'l-! of Fig. 9;

Fig. 8 is a View in vertical section taken substantially along the line 88 of Fig. 7;

Fig. 9' is a view in vertical section taken along the line @9 of Fig. 5;

Fig. 10 is a fragmentary view in vertical section taken substantially along the line Ill-l0 of Fi 2;

Fig. 11 is a fragmentary view in perspective section taken substantially along the line ll- I, of Fig. 10;

Fig. 12 is a view similar to Fig. 7 showing a modification of the coupling;

Fig. 13 is a view similar to Fig. 12 but certain parts being removed and others cut away for purposes of illustration;

Fig. 14 is a view in perspective of a motion picture camera embodying the invention;

Fig. 15 is a fragmentary view in horizontal section taken substantially along the line l5l5 of Fig. 14; and

Fig. 16 is an enlarged view in perspective of the diaphragm adjusting unit of the camera shown in Figs. 14 and 15.

As shown in Figs. 1 to 11, a camera 2, as for example a focal plane shutter, interchangeable lens-diaphragm type camera, embodying the invention may comprise a camera case 4 of a well known form comprising the usual film-receiving means and film-feeding means (not shown) including film-winding knob 6, film-rewinding knob 8, the film being moved on operation of the knob 6 past a focal plane shutter (not shown) operated by shutter release button it] and controlled by the usual shutter speed adjustment means including shutter speed adjusting knob l2.

A photoelectric or other light sensitive exposure meter [4 is detachably secured in any desired manner to the top wall [6 of the camera case 4.

The camera also includes a conventional lensdiaphragm mounting tube I8 secured to and projeeting forwardly from the camera case. This tube is provided at its inner end with an inturned flange 20 having a plurality of radial notches 22 to receive the radially and arcuately beveled mounting lugs 24 on the reduced inner end of the barrel of the usual interchangeable lensdiaphragm unit 26 having diaphragm adjustment or exposure opening setting means including an adjusting or setting ring 28 turnably mounted on the barrel of the unit.

The present invention provides simple and inexpensive means adaptable to the conventional camera thus far described for interconnecting the shutter speed adjustment means or knob l2 with the diaphragm adjustment or exposure opening setting means in such manner that manipulation of the shutter speed adjustment means will automatically effect an adjustment of the setting of the diaphragm adjustment or exposure opening setting means but the adjustment of the diaphragm will not effect adjustment of the shutter speed adjustment means.

As shown in Figs. 1 to 11, such means may comprise a drum 32 having a central opening to permit its placement over the lens mounting tube 18 and being secured to the front wall of the camera case 4. The drum provides a ring 34 coaxial with the lens mounting tube l8 and the ring has an arcuate opening 36 in its upper portion to expose the annular rim 38 of a circular plate or drum 4|] journaled in the ring 34 and on the lens mounting tube IS. The rim 38 is provided with a marker 42.

A circular plate or drum 44 having an annular rim 46 of preferably the same radius as the ring 34, is also journaled on the lens mounting tube I8 forwardly of the drum 32. The rim or ring 46 is provided with a light rating or scene brightness scale 48 corresponding to the direct scene brightness or light rating readings of the exposure meter l4 and cooperating with the marker 42 on the rim or ring 38. The front face of the circular plate 44 is provided with a film speed scale 50, the indicia of the scale cooperating with notches in the rim or front face of the circular plate 44. Notches 52 and the corresponding indicia of the scale 50 are equally spaced from each other by the same number of angular degrees.

The ring 34 may for convenience be provided with an exposure opening or diaphragm setting scale 54, although this is not essential since the lens diaphragm unit may have the usual diaphragm setting scale 56 cooperating with the pointer 56 carried by the adjusting ring 28.

Means for detachably coupling the circular plate 44 to the diaphragm adjusting ring 28 may 4- comprise the coupling ring 66 secured on the lens mounting tube i8 as by a clamping ring 62 which may be internally threaded for threading on external threads at the forward end of the lens mounting tube. The coupling ring 50 is provided with a notch or opening '64 to receive the coupling lug 36 extending rearwardly from the adjusting ring 28. The coupling ring 60 is also provided with an outwardly directed radial lug G6 which is pivotally secured to a coupling finger 68 having a lug ill for interengagement with the notches 52 in the circular plate 44. The drums 32 and 49 are interconnected with the shutter speed adjusting knob 12 for simultaneous movement therewith by the mechanism now to be described.

In the conventional focal plane shutter camera 1eadjusting knob 12 is secured to a stud having on lower end a plate 12 carryin a depending pin '54, the knob on raising disengaging the pin 14 from a companion part (not shown). On turning of the knob 42 the raised pin 14 is then rotated relative to a companion part and then depressed to re-engage the companion part in a different angle or position thereby to determine a diflerent exposure time or shutter speed. In accordance with this invention the knob i2 is interconnected with the shutter speed adjusting plate 12 by a shaft 16 splined to a beveled gear it so that the shaft may be raised to raise the plate E2 on lifting of the knob l2 and the beveled gear "iii turned with the plate 72 on turning of the knob l2. The beveled gear 78 is held axially on the shaft 76 between the top wall It of the camera case 4 and an arm 88 of a bracket 82 secured to the inner surface of the wall it, the arm as being apertured to receive the shaft 15 and being spaced from the wall E8 to underlie the beveled gear 1 8. The knob 12 and the shaft 16 are made hollow, and the plate 12 is provided with a central opening, through which the shutter release button 10 projects and is connected in the conventional manner to the shutter release mechanism. The knob i! has a marker 85, Fig. 3, cooperating with a shutter speed scale 86 inscribed on the top wall l6 of the camera on a plate secured to the top wall and underlying a marker containing ring 88 of the knob l2.

It is to be noted that the indicia of the scale are not spaced at equal angles because the usual type of shutter speed adjustment means requires that the adjustment knob be turned at progressively different angular distances in moving from one shutter speed setting to another. Shutters and shutter speed adjustment means wherein the adjustment from one shutter speed setting to another is accomplished by equal angular movements of the adjusting knob are however known (see for example the patent to Kuppenbender 2,117,429), and such shutter and shutter speed adjustment means may be used if desired in the camera constructed in accor ance with the present invention. However, it is preferred to employ the shutter adjustment means of the conventional focal plane shutter camera for by such employment a minimum modification of the present camera construction is required. In order to permit different angular movements of the shutter speed adjusting knob 12 to effect equal angular movements of the drums 46 and 38, the beveled gear '18 is provided with teeth 98 which are spaced at unequal angular distances corresponding to the indicia of the scale 86, as shown in Fig. 11, there being one tooth 96 for each indicia of the scale 86 excepting only the time exposure indicia T since when set for time exposure the opening and closing of the shutter is determined by the photographer rather than by the camera. 7

The beveled gear I8 constitutes the driving gear of an intermittent motion mechanism of which the driven gear 92 comprises a beveled gear having tooth spaces angular-1y spaced equally about the periphery of the gear. The gear 92 is journaled on the pin 94 secured in any convenient manner to the front wall 66 of the' camera case 4. The gear 92 is pinned to a spur gear 98 also journaled on the pin 84 and meshing with a gear I00 journaled on pin I62 secured to the camera wall 96. The gear I88 in turn meshes with a gear I04 fixed to a stud shaft I06, Fig. 7, projecting through the front wall 96 of the camera case. The front wall 96 is provided with a circular outwardly extending flange I08 forming a journal for the shaft I08, the shaft being secured against axial movement by a spacing washer I I0 between the gear I04 and the inner surface of the wall 96 and by radial pins II2 externally of the wall. The washer I I4 is interposed between the pins H2 and the flange I88. The shaft I06 is provided with diametrically opposite forwardly extending lugs II6 received in complementary openings in complementary and diametrically opposite slots H8 in a spur gear I20. The lugs II6 serve as a splined connection between the shaft I06 and the gear, I causing the gear to rotate with the shaft but permitting it to move in a direction axially of the shaft. The gear I20 is provided with a reduced forwardly projecting portion or annular flange I22 having forwardly directed preferably V-shaped teeth I24. The teeth I24 register with the like teeth I26 formed in a rearwardly directed flange or reduced portion I28 of a gear I38. The gear I88 is journaled on a pin or stud I32 which passes through the gear I20 along the axis thereof and is threaded at its rear end into the shaft I86. A coil spring I34 interposed between the shaft I86 and the rear face of the gear I20 urges both gears outwardly, the gears being retained on the pin I32 by a washer I36 and a head I38 of the threaded pin I32.

The shaft I06 is mounted in offset radial relation to the axis of the rings 38 and 46. The ring 38 is provided internally with gear teeth I40 meshing with the gear I28, and the ring 46 is similarly provided with gear teeth (not shown) meshing with the gear I38. The end wall of the drum 40 which provides the ring 38 is provided with an arcuate slot I42, as illustrated in Fig. 9, to permit passage of the shaft I86 and the reception of the gear I20 and permit the drum to rotate with respect to the fixed shaft I06.

Whenever the shaft I66 is rotated the gear I20 rotates with it and through the toothed flanges I22 and I28 the rotation of the gear I20 is transmitted to the gear I so that the rings 38 and 48 rotate together. Whenever the ring 46 is turned, the shaft I86 being locked against movement, the V teeth I26 of the annular flange I28 will act as cams forcing the gear I20 inwardly against the axis of spring I34 and the teeth I26 will therefore ratchet past the teeth I24, thereby permitting the ring 46 to be rotated manually without rotating the ring 38.

The shaft I6 is held against rotation except when the knob I2 is raised and turned by the engagement of the pin I4 in the companion part (not shown), as is conventional in the cameras of the type shown in Figs. 1 to 11. Hence the bevel gear 18 is held against rotation except when the knob I2 is raised and turned to change the shutter speed adjustment. Hence the shaft I06 is locked against movement except when the knob I2 is raised and turned. If desired the bevel gears I8 and 92 which constitute in effect an intermittent motion mechanism, may be provided with the usual locking ring surfaces so that whenever ring 46 is turned manually the force tending to turn gear I 20 will not be applied to the shaft I6.

In operation, the scene brightness is measured in the usual manner by the exposure meter I4, the light rating indicating of the scene brightness is read directly from the needle of the exposure meter and the ring 46 is turned manually by swinging the coupling finger 68 arcuately until indicia of the scale 48 corresponding to the direct reading of the exposure meter is aligned with the mark of 42 on the ring 38. This turning of the ring 46 serves through the coupling finger 68, the ring 60, and the lug 30 to turn the diaphragm setting or exposure opening control ring 28 to the correct exposure setting.

When the film was originally loaded into the camera the coupling finger 68 was released from the control plate 44 by swinging it forwardly therefrom and the coupling ring 60 or the control plate rotated to bring the coupling finger into alignment with the notch corresponding to the proper film speed rating of scale 50 corresponding to the rated speed of the film placed in the camera. If the lens unit has a built-in filter or a separate filter is employed with the lens, the speed rating of the film will, as well understood, be reduced by the filter factor and therefore as different filters are employed the coupling ring 60 and the control plate 44 would be adjusted relatively to couple them together at the proper film speed rating corrected for the filter factor.

It is to be noted that the marker 42 on ring 88 is angularly set in accordance with the setting of the knob I2 of the exposure speed adjustment means. As previously indicated, the ring 46 is set, on the measurement of scene brightness, to bring the corresponding scale 48 into alignment with the pointer 42. If after this setting of the rings 38 and 46 has been accomplished for a particular scene brightness, it should be desired to change the shutter speed adjustment, the raising and rotation of the knob I2 causes rotation of the shaft I06 through the gear train consisting of the gears I8, 92, 98, I00 and I04. The rotation of the shaft I66 causes simultaneous rotation of the gears I20 and I36 and consequent simultaneous rotation of the rings 38 and 46. The rotation of the ring 46 causes, as previously indicated, simultaneous rotation of the diaphragm adjusting ring 28 and hence automatically resets the exposure opening to the correct value.

On a change in the scene brightness, the rotation of the control plate 44 brings a corresponding new number of scale 48 in alignment with the marker 42. The gear I30 is rotated, but the exposure speed adjustment means being locked in position, the shaft I86 is also locked and consequent rotation of the gear I30 serves automatically to disconnect the gear I30 from the gear I20 and consequently the ring 38 remains stationary.

The coupling between the shaft I86 and the gears I28 and I30, as shown in Figs. 7 and 8, requires sufficient space to permit the gear I20 to move axially sufficiently to engage and disengage the toothed annulus I22 and I28. In some instances it may be necessary or desirable to provide a more compact coupling, as illustrated in Figs. 12 and 13. As shown in these figures, the shaft I06 is journaled in sleeve I44 which is friction fitted in the circular flange I of the front wall 96 of the camera case. The sleeve has an annular mounting flange I40 at its inner end and receives at its forward end a spacing washer I43 and the gear I20. The gear I20 is keyed in the usual manner, not shown, to the sleeve 44. A collar I50 is mounted within the sleeve I44 at its forward end and has on its opposite end faces V-shaped teeth I52 and IE4. The collar 50 is also provided with a radial lug I56 received in a longitudinal slot I53 in the sleeve I44.

The shaft I 06 terminates within the sleeve 44 and has its forward end face provided with V-shaped teeth I60 complementary to the teeth I52 of the collar I50. The collar IE0 is slidably mounted on a pin or stud I02 threaded into the shaft I06 and projecting forwardly therefrom. The gear I30 is mounted on the pin I62 and has its rear face provided with V-shaped teeth I04 complementary to the teeth I54 on the forward face of the collar I50. The gear I30 is held against outward movement on the pin I62 by a washer I66 and the enlarged head I08 of the pin. A coil spring I'I0 bearing against the rear face of the gear I30 and received in a circular recess in the collar I50 normally urges the collar to the position shown in Fig. 12 in which the teeth I52 of the collar mesh with the teeth I00 of the shaft I06. The coil spring also serves to maintain the gear I30 against the washer I06 and therefore in sufficiently spaced relation to the gear I to permit these gears to rotate relatively. It will be understood that the gears I20 and I of the couplings shown in Figs. 12 and 13 mesh with the internal gear teeth of the rings 38 and 46 as in the embodiment shown in Figs. 1 to 11. Hence when the shaft I00 rotates, the interengaging teeth I52 and I00 exert a camming action in an axial direction on the collar I00 against the action of the spring I70, the friction fitting of the sleeve I in the circular flange I00 insuring the axial movement of the collar I prior to the rotation of the sleeve I44. When the collar I50 is thus urged axially outward, it couples the sleeve I44 to the gear I30 so that the sleeve I44 turns with the shaft I06 and the sleeve drives both the gear I20 and the gear I30. However, the gear I30 is normally disconnected from the collar I50, due to the action of the spring Ilil, and hence the gear I30 can be freely turned, by retating the ring 46, and without causing rotation of the gear I20.

It will be evident that the exposure opening may be preselected by first rotating the control plate 44 or coupling ring to the desired exposure opening value and thereafter, on measurement of the scene brightness, the ring held against rotation while the speed adjustment knob is rotated until the marker 42 is aligned with that value of scale 40 which corresponds to the measured scene brightness.

As shown in Figs. 14 and 15, a motion picture camera embodying the invention may comprise in a conventional motion picture camera construction including a front lens and adjustable diaphragm unit I12 received in the usual mounting tube I14 projecting forwardly from the front wall I16 of the conventional camera cas ITS. A drum I corresponding to the drum 32 of the camera shown in Figs. 1 to 11 is mounted on the front wall I16, the ring flange of this drum being concentric with the lens tube I14. A ring I82 corresponding to the ring 30 is journaled in the ring flange of the drum I80 and is provided with a marker I84 corresponding to the marker 42 and exposed within an arcuate slot I86 in the ring flange of the drum I80. A control plate I88 similar to the control plate 44 is mounted on the lens tube I74 adjacent the drum I80 and the ring I82 and its external surface or its ring flange is provided with a scale I90 corresponding to the light rating scale 40 and a film speed scale I92 corresponding to the speed scale 50. The control plate I08 is also provided with a series of notches I94 aligned with the indicia of the film speed scale I02 and corresponding to the notches 52 of the camera shown in Figs. 1 to 11. The control plate I08 is detachably coupled to the diaphragm adjustment means or exposure opening control ring I96 as by a coupling finger I98 pivoted on a lug 200 extending radially from the ring I96. the coupling finger I92 corresponding in shape and form to the coupling finger 60 as heretofore described.

The ring I82 is externally toothed as indicated at 202 in Fig. 14 and the ring flange of the control plate I08 is also provided with external gear teeth as indicated at 204 in Fig. 14. A shaft 206 is mounted in any convenient manner in the front wall I76 of the camera case and projects both internally and externally therefrom. On its outer end the shaft carries gears 200 and 210 corresponding to the gears I20 and I30 and similarly coupled to the shaft 200 as illustrated in Figs. 7 and 8 or Figs. 12 and 13. The gears 208 and M0 mesh with the external teeth 202 and 204 of the ring I82 and the control plate I88.

On its inner end the shaft 205 has secured to it a beveled gear 2 I 2 which meshes with the beveled gear 2I4 on the shaft 2I6 journaled in a bracket 2 I0 secured internally of the camera case to the front wall H0. The shaft 2I6 is coupled by beveled gears 220 to a shaft 222 journaled in brackets 224 secured to the sidewall 223 of the camera case I10. The shaft 222 is coupled by intermeshing beveled gears 228 to the adjustable shaft 230 by means of which the camera is set to take pictures at different framing frequencies. The shaft 230 projects from the sidewall 226 of the camera case. Externally of the case the shaft carries a latch lever and pointer 232 which is secured to an adjusting knob 224 splined to the shaft and normally urged inwardly so that the latch 230 may engage one of the keeper notches 240 of the plate 242 secured to the outer surface of the wall 226 of the camera case. The camera adjacent the plate 242 is inscribed with suitable indicia indicating the setting of the shaft 230 to take pictures at sixteen frames per second or 32 frames per second or 64 frames per second. The latch 232 serves to hold the shaft 230 and consequently the shafts 222, 2I6 and 206 against movement when the control plate I80 is adjusted by manipulation of the finger piec I08.

The use and operation of the motion picture camera shown in Figs. 14 to 16 will be evident from the description of the use and operation of the camera shown in Figs. 1 to 11.

A housing 244 for the gears 208 and 2H] and the coupling between them may be secured in any convenient manner to the front wall I16 of the camera case and extend over the gears in juxtaposition to the drum I00, the ring I82, and control plate I90. If desired the housing 244 may be made integral with the drum I80, the ring flange of the drum being somewhat larger in radius so as to extend at one side thereof over amazes the external teeth along the ring flange of the drum I90 as well as the external gear teeth on the ring I82.

From the foregoing description it will be evident that applicant has provided in a camera control means for so relating the various adjustable members of the camera, as for example the shutter speed adjustment means or exposure interval setting means and the diaphragm adjustment means or exposure opening setter, that setting of the control relative to its shutter speed adjustment means in accordance with scene brightness, as determined by the direct reading 01 the exposure meter, to automatically set the camera for taking of the picture at the proper exposure opening for diaphragm adjustment. Applicant has provided in such a camera control means as above stated wherein the camera having been set according to the scene brightness, the proper exposure opening or diaphragm adjustment will be automatically varied or changed the proper amount by the adjustment of the shutter speed adjustment means. He has also provided in a focal plane shutter, interchangeable lens and diaphragm type camera, control means which are governed by the measurement of the scene brightness to effect the proper setting of the exposure opening or the diaphragm adjustment to agree with the selected shutter speed setting or adjustment; and in a multi-speed motion picture camera control means which on adjustment in accordance with the scene brightness, as measured by exposure meter, automatically sets the exposure opening or diaphragm adjustment to the proper value for the selective shutter speed framing frequency.

It will be obvious that changes may be made in the form, construction and arrangement of the parts without departing from the spirit of the invention or sacrificing any of its advantages, and the right is hereby reserved to make all such changes as fairly fall within the scope of the following claim.

What I claim is:

In a camera having a lens tube, exposure speed adjustment means and exposure opening adjustment means, a first control member rotatably mounted on said lens tube and connected to said speed adjustment means for adjustment therewith, a second control member rotatably mounted on said lens tube in juxtaposition to said first member, both of said members being rings having 10 internal gear teeth and journaled on the lens tube, a releasable connection between the second control member and said opening adjustment means to permit relative adjustment thereof, means for governing the adjustment of said members relatively in accordance with scene brightness, means for governing the adjustment oi! the second member and said opening adjustment means relatively in accordance with film speed, means for holding the speed adjusting means against movement, which means are releasable to permit adjustment of the speed adjusting means and a releasable drive connection between said members for causing automatic adjustment of the opening adjustment means on adjustment of the speed adjustment means and permitting adjustment of said opening adjustment means independently of said speed adjustment means, said releasable drive connection comprising a stud, a gear journaled on said stud and meshing with the teeth of one of said rings, a rotatable shaft, a second gear meshing with the teeth of the other ring and splined to said shaft for rotation therewith and for axial movement relative thereto toward and from the first gear, spring means urging the second gear toward the first'gear, and interengageable camming teeth on said gears normally urged into engagement by the action of the spring means on said second gear on rotation of the shaft and causing automatic disconnection of the gears on rotation of the first gear.

DENNIS B. DORSEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 883,607 Andrews Mar. 31, 1908 1,543,208 Fairchild June 23, 1925 1,546,060 Carmine July 14, 1925 1,623,998 Cooke Apr. 12, 1927 2,020,036 Marks Nov, 5, 1935 2,031,321 Kuppenbender Feb. 18, 1936 2,117,429 Kuppenbender May 17, 1938 2,194,152 Riszdorfer Mar. 19, 1940 2,209,156 Fischer July 23, 1940 FOREIGN PATENTS Number Country Date 147,573 Austria Nov. 10, 1936 

